Sottntkreception system



July 12, 1927. ,635, 68

J. E. AIKEN SOUND RECEPTION SYSTEM Filed Jan. 25. 1924 INVENTOR w ESSES:

5,4 Josga 4/1690 ATTORNEY Patented July 12, 1927. 1,635,563

UNITED STATESVPATENT OFFICE.

JOSEPH E. AIKEN, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE i ELECTRIC & MANUFACTURING COMPANY, A CORPORATION'OF PENNSYLVANIA.

SOUND-RE CEPTION SYSTEM.

Application filed January 25, 1924. Serial NIL-688,391.

My invention relates to apparatus for the the speaker from the audience might not be 65 translation of sound into vibratory electric obstructed. r t Furthermore, when the sensitivity'of an Broadly speaking, the object of my invenordinary microphone was increased, or when tion is to construct a system for converting suiiicicnt amplification was applied to its outsound vibrations into vibratory electric'alcun put, it wa f nd th tv th i h rents, which system shall respond to sound sponded not only to the speakers voice but from a certain source more readily than to also to extraneous sounds of many kinds, inound fro th r urces eluding echoes and applause by the audience,

10 More specifically, the object of my invento such an extent that'the reproduction of tion is to produce a sound-responsive device the speakers voice notinfrequently was obcooperating with sound-reflecting and soundscured and made entirely unintelligible. absorbin means which'shall be adapted to My invention provides means for impressbe place upon ornear rostrum at public ing insubstantial amount of sound wave en- 5 exercises, and to be responsiveto sound from ergy upon the microphone transmitter when a speaker at such public exercises and not rethe transmitter is at the desirable distance sponsive to extraneous sound sy such as a from the speaker, and it further provides plause, echoes and other disturbing noises, sound-absorbing means. whereby undesired 4 thereby giving a much more accurate copy sound waves are restrained'from influencing 20in vibratorelectric currentsof the sound the microphone. v

waves'produced by'the speakersj voice. Other objects and structural details ofmy Inthe development of the} prior art of invention'will be'apparent'from thejoll telephony, the. microphones have, in great ing description, when read in' onnection with part, been of the type'ofthe, simple telephone the accompanying drawings, wherein transmitter suit-able'for the transmission of Figure-1Iisa-viewin elevationlof my de the voice'offa speakerfroni a locationclose .vicein operative relation 3 to associated iobto the transmitter, IRelati'vely few inicrojects,and

phoneidevices have been San ana; for the re- Fig.2 is a planf view crane 'maa iiiiit ception of speechwhenplaced atasubstan of Fig. 1,, Q 1 30 tial distance froni the speakers vo ce, Be- 1 Fig. Lshows a rostrum},.aspeaker 2; a

cause of the lack ca ual devices,ftherecep-- curved sound reflector 3 i n combinatioiifwith tion of sound. fromla speaker at-apublic a microphone l'to which. is attachedan outexercise and its 'conversion into. vibratory going electric circuit.5. .The retlector.3,and electric currentssuitablelfor such purposes the microphone sr'apie eiabi placedujust- 35 as that, of modulating .the,ou tput of a radio. behind the footlights 6, when ,footlights are sending apparatus has been found ditficult. present on ;t he rostrum, or they maybe hung .Because. of this,lack,.the broadcasting 10f l:'rom the ceiling, or otherwise disposed in public.speakirn exercises by radio sending front of the speaker 2, with'theaxisof the 4 apparatus has een hampered ,and retarded reflector directed toward sound-ab b -the deficiencies of theresponseof availsorbentcurtainfzis placed behind the speaker ali le microphones. The..miicroph0ne. trans, 3. .-The" reflector can. guide to themicromitters, which were developed for telephonic phone allthe sounds; which originate .Withconversation, have: relatively small mouth in a certain space, tapering toward the repieces for the collection .,of.the speakers fiector, which is herein designatedas the voice. They do not give,adequate response; sound-reflective beam ofthe reflector, The to the speakers voice when placed more than curtain 7 is madesufiiciently large in size to a few inches from his face. Therefore, when cover the area, at its position, of the soundit was desired to translate the sound waves reflectivebeam of reflector 3. I of the speakers voice into vibratory electric Indescribing the reception of'soundby' a currents for the above purpose, difliculty was microphone, .it is convenient to distinguish experiencedby reason of the lack of sensi-' between two types of sound. Thesound emativity of the microphones. These must nec nating directly from the source, which it is essarily be placed at a substantial distance desired to copy accurately into vibratory from the speaker in order that the View of electric currents, may be called the primary sound. The other sounds, such as echoes, applause and' other extraneous noises, may be called secondary sounds. The purpose of my invention, then, is to obtain a maximum "response of'a microphone-to primary sounds substantial distance may intervene between them.

The increase in sound energy received by microphone .9, as compared to the energy receiv'ed'byan ordinary transmitter in the same position, is approximately in the ratio of the'area of the front opening-of the re fle'ctor. 3 to.the'area of the front opening of themicrophone withwhich it is compared. By this means, Iam able to obtain sufiieient response of'the microphone when it is removed to a position where it will not interfere with" the; view of the audience, even though the distance from the speaker tothis positionzbe fairly great.

I'also increase the'ratio of response to primary sound, as compared 'to'the response to. secondary sound, by the reflecting powers.

of the reflector 3; Th'sound from the predetermined source enters the reflector 3, as shown, andis' brought toa-Vfoeus upon the transmitter-4; Sound striking the reflector from'theoppositeside is reflected away by the outer surface of reflector 3 and'do'es'not impinge upon the -xnicrophone 4, which .lies in a sound shadow with respect" to sound from-the: audience. lines 11, .ivhich are the path of'travel of .such a sound wave.

Other sounds which may originate upon the same rostrum, but in'a'position at. one

side of'thbsp'eaker', may enter the reflector 3, as shown by lines 12, but such sounds are" not brought to a-focus upon the microphone 4 and, therefore, do not atiect the microphone appreciably. Sounds-originating in the audience'may' strike reflelctin surfaces at'the-rear oftherostrum and thereby be reflected; into the refl'ector 3 and'be concentratedby it u n the mieroplione' li To prevent this action, the"cur tain*7-'is providedbehind the s e'aker' 2.1 This curtain is made ofa sound fa sorbe'nt material and it clamps out sounds striking it, thereby, preventing the reflection of extraneous sounds into the reflector? from adirection which would allowiit to concentrate those sounds upon the microphone 4.

This is indicated by' Inasmuch as the aoilnd-seazj-itire element ofthe microphone t: has a linite size. the microphone is responsive to sounds which are brought to a focus m'cr a dcliuilr p rtion ofits area. The locus ot' points from which sound will be'brought-to a focus up n the tiuilc area of the :Hillltl-t'eiifiill\t' element Of-'th0 microphone l v the lllii'ul occupies the lrustuur of a cone whose small end eutcrs'thc reflector. 'l'hiscone ir'. the boundary f the sound-reflective beam of the combination of the reflector and the microphone t. this cone wiil hc'reccired by the microphone, and. therefore. the source to which the. microphon is desired to icspoud must. be placed therein. Also, any sound reflected by a. reflecting surface therein will aflcct the microphone. For this reason, the soundabsorbeutcurtain T is made of a size suflicicntto cover the sound-reflectire beam of reflector 3.

By means of this invention, 1 am'able to secure an accentuated response of'a microphone to predetermined sounds, thereby greatly increasing the ratio of such response to the response caused by other sounds.

My device is particularly adapted to the reception of, and response to, the sounds produced by a speaker at a public exercise, thereby producingfan'accurate copy of 'the spealcers voice, relatively unaffected by c);- traneous noises, by" means of apparatus which is inconspicuous to the audience.

While I have shown only one embodiment of my invention in the accompanying drawings," itis capable of various changes and modifications without departing from the spirit thereof, and it is'dcsircrl', therefore, that'only such. limitations shall be imposed thereon as are indicated in the prior art or in-thc'appendcd claim.

I- claim as my invention:

A sound collectingsystem [or use upon a rostrum to cotlect the sound of'a spcakers voice1but to shut' out the sounds set up by anaudience, comprising a reflector having a focus disposed between the audience and the speaker sutliciently spaced from the speaker to provide an unobstructed viewof him and directed toward the speaker, a microphone at the focus of the reflector, and a loosefabric supported behind the speaker, said fabric being a'n etiicien't sound absorber and poor reflector, thereby reflecting no sounds from the audience upon the reflector.

In testimony whereof, 'l have -hereilnto subscribed my name this ilzat day of January, 1924.

JOSEPH AIKEN.

Sounds from any point in 

